Shopping cart chassis

ABSTRACT

A shopping cart chassis is provided with at least one tubular frame member. At least a first part of the length of the frame member has a wall with a hollow cylindrical configuration defining an annular transverse cross-section. At least a second part of the length of frame member has a wall with a hollow configuration defining an elongate transverse cross-section having a longer dimension and a shorter dimension. A second part of the frame member is oriented so that the longer dimension of the elongate transverse cross-section is generally parallel to the direction of the force of gravity when the shopping cart is in its normal use orientation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/937,024, which was filed on Sep. 9, 2004.

TECHNICAL FIELD

This invention pertains to a shopping cart which has a chassisconstructed from one or more tubular frame members.

BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIORART

A conventional shopping cart has a one-piece or multi-piece chassis thatis mounted to swivel casters and that typically supports at least a wireor polymer basket. One such conventional shopping cart design isillustrated in the U.S. Patent Publication US 2004/0084863 A1 publishedon May 6, 2004 by the U.S. Patent and Trademark Office. The chassis forthat cart is fabricated from a plurality of tubular frame members.

The tubular frame members are conventionally formed from hollow, steeltubing, and the frame members are preferably and typically connected orjoined together by welding.

Another shopping cart design has a chassis formed from a single lengthof tubing that is bent into the desired configuration.

The cost of the shopping cart is dependent upon, among other things, theamount of the steel that is used in the tubular frame member or membersof the chassis. It would be desirable to provide an improved design fora shopping cart or a portions of shopping cart in which the amount ofsteel in one or more tubular frame members could be minimized, or atleast reduced.

It would be particularly desirable to provide an improved design inwhich the wall thickness of a hollow tubular frame member could bereduced, at least over a portion or portions of the length of thetubular frame member.

Because shopping carts are typically subjected to various dynamic andstatic loads, including loads imposed by goods being carried, as well asby loads resulting from impacts, it would be advantageous to provide animproved design for a shopping cart chassis or portions thereof whereinthe chassis could withstand the anticipated dynamic and static loadswithout failure or other damage.

Although it would be beneficial to provide an improved design for ashopping cart chassis (or portions thereof) that could be made from atubular frame member having a reduced amount of steel or otherstructural material, it would also be desirable to provide such animproved design that can employ tubing that is of a conventional typewhich is readily available in the tubing market—rather than requiringspecial non-stock tubing.

The present invention provides an improved shopping cart chassis whichcan accommodate designs having the above-discussed benefits andfeatures.

BRIEF SUMMARY OF THE INVENTION

A novel arrangement for at least a portion of a shopping cart chassis isprovided which can reduce material costs while providing a chassisstructure that can withstand the anticipated dynamic and static loads.

Further, the novel chassis arrangement of the present invention may bemade with stock tubing that is readily available from tubingmanufacturers.

The improved design readily accommodates the connection of oneload-bearing portion of a tubular frame member to another portion of thesame tubular frame member in the chassis.

The improved design can be relatively and easily manufactured withoutrequiring the use of unusual and expensive manufacturing techniques.

The improved design can withstand the anticipated dynamic and staticloads imposed on the chassis.

According to one aspect of the invention, a shopping cart chassis isprovided with at least one tubular frame member.

At least a first part of the length of the frame member has a wall witha hollow cylindrical configuration defining an annular transversecross-section. At least a second part of the length of the frame memberhas a wall with a hollow configuration defining an elongated transversecross-section having a longer dimension and a shorter dimension. Thesecond part of the frame member is oriented so that the longer dimensionof the elongate transverse cross-section is generally parallel to thedirection of the force of gravity when the shopping cart is in itsnormal use orientation.

In a presently preferred embodiment, the frame member second part wallthat defines the elongated transverse cross-section has twospaced-apart, parallel straight sections joining two semi-circularsections.

In a preferred form of a chassis incorporating the invention, thechassis frame member has one or more bends so that one or more portionsof the frame member are adjacent to each other at a location orlocations where the portions can be connected. In one preferredembodiment there is one connection of one part of the frame member toanother part of the frame member. In particular, the frame member has atleast a first part that includes a first connection portion, and theframe member has at least a second part that includes a secondconnection portion. Each first and second connection portion defines agenerally longitudinal central axis. The first connection portion isdisposed adjacent the second connection portion so that the longitudinalcentral axes of the connection portions are aligned generally parallel.A weld joins the first connection portion with the second connectionportion to provide a strong chassis.

The novel structure of the present invention permits the use of atubular frame member with a reduced thickness wall. This requires lessmaterial, and reduces costs. The flexural rigidity of one part of theframe member in a particular loading direction of interest may actuallybe increased even though the flexural rigidity of that part of thetubular frame member with respect to a certain other loading directionsmay be decreased where higher flexural rigidity is not required becausethe loading in such other directions is not anticipated to be as high,or where the chassis otherwise provides increased strength or rigidityas a result of connection with another portion of the tubular framemember or with a reinforcing member of the chassis. However, byappropriate orientation of an elongate transverse cross-section of theone part of the tubular frame member, the one part of the tubular framemember can exhibit sufficient flexural rigidity in a desired directionwhere needed to accommodate the imposed load.

Numerous other advantages and features of the present invention willbecome readily apparent from the following detailed description of theinvention, from the claims, and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings that form part of the specification, and inwhich like numerals are employed to designate like parts throughout thesame,

FIG. 1 is a perspective view of a shopping cart which incorporates achassis embodying the present invention;

FIG. 2 is a perspective view of the chassis of the shopping cart shownin FIG. 1; and

FIG. 3 is a transverse cross-sectional view taken generally along theplane 3-3 in FIG. 2.

DETAILED DESCRIPTION

While this invention is susceptible of embodiment in many differentforms, this specification and the accompanying drawings disclose onlyone specific form as an example of the invention. The invention is notintended to be limited to the embodiment so described, however. Thescope of the invention is pointed out in the appended claims.

For ease of description, a shopping cart incorporating this invention isdescribed in the normal (upright) operating (use) position, and termssuch as upper, lower, horizontal, etc., are used with reference to thisposition. It will be understood, however, that a shopping cartincorporating this invention may be manufactured, stored, transported,used, and sold in an orientation other than the position described.

Figures illustrating the shopping cart show some mechanical elementsthat are known and that will be recognized by one skilled in the art.Detailed descriptions of such elements are not necessary to anunderstanding of the invention, and accordingly, are herein presentedonly to the degree necessary to facilitate an understanding of the novelfeatures of the present invention.

FIG. 1 illustrates a shopping cart 10 which includes a chassis 12 of thepresent invention. The chassis 12 is mounted to four wheel assemblies orcasters 14, and the chassis supports an upper basket 16 and a handlestructure 18. Mounted to the lower portion of the chassis 12 is a lowerrack or platform 20. The casters 14, basket 16, handle structure 18, andlower rack 20 may be of any suitable conventional or special design, thedetails of which form no part of the present invention. Further, somefeatures, such as a lower rack 20, may be omitted in certainapplications.

The chassis 12 is illustrated separately in FIG. 2. The chassis 12, inthe preferred embodiment illustrated in FIG. 2, is formed from a singletubular frame member which is bent and cold-formed as necessary toprovide the illustrated configuration.

In a presently preferred, contemplated, commercial embodiment, thechassis 12 is a single, tubular frame member consisting of plain carbonsteel tubing which, after welding as described in detail hereinafter,may be chrome-plated or powder-coated. In a presently contemplated,preferred, commercial embodiment, the tubular frame member is initiallyprovided as nominal one inch outside diameter, 14 gauge round tubing ofa predetermined length. The wall thickness of the tubing, prior to anybending or other cold-forming processes, is about 0.070 inch. Prior tobending and forming the tubular frame member into the configuration ofthe chassis 12 illustrated in FIG. 2, one or more parts, sections, orregions 30 of the length of the frame member are cold-formed to alterthe transverse cross-section of the tubular frame. As shown in FIG. 3,each part, section, or region 30 of the tubular frame member has anelongate transverse cross-section having a longer dimension and ashorter dimension. The longer dimension is generally parallel to thedirection of the force of gravity when the shopping cart is in itsnormal use orientation. In a presently preferred, contemplated,commercial embodiment, the tubular frame member wall that defines theelongate transverse cross-section has two spaced-apart, parallel,straight sections 34 joining two semi-curricular sections 36.

Each elongate transverse cross-section part, section, or region 30 ofthe tubular frame member of the chassis 12 is about 13 inches long inthe presently preferred, contemplated, commercial embodiment. Theelongate transverse cross-section regions 30 of the tubular frame membermay be conveniently formed in a conventional incline press bycold-forming the tubular wall into the elongate cross-sectionalconfiguration. Both regions 30 of the chassis 12 may be cold-formedsimultaneously in an appropriately configured incline press. Othermanufacturing techniques could also be used to form the elongatedtransverse cross-section regions 30.

As it can be seen in FIG. 2, at each end of each elongate transversecross-section region 30, there is a transition portion 40 connecting theelongate transverse region 30 with the remaining, annular transversecross-section of the adjacent portions of the tubular frame member ofthe chassis 12.

The remaining portions of the chassis tubular frame member which extendbeyond the elongate transverse cross-section regions 30 and transitionportions 40 have a generally uniform, annular cross-section, but arebent as necessary to form the overall configuration of the chassis 12.In particular, in a presently preferred, contemplated, commercialembodiment, at least each end portion, end part, or end segment 50 (FIG.2) extends from a bend and is disposed generally horizontally so that itis parallel to one of the elongate transverse cross-section regions 30.Each end portion 50 is disposed on top of one of the regions 30 as shownin FIGS. 2 and 3, and a weld 60 (FIG. 3) joins the tube regions 30 andtube end portions 50. The weld 60 is preferably located on the insideportion of the chassis 12. The weld 60 could also be located on theoutside portion of the chassis 12, or welds 60 could be provided both onthe inside and on the outside of the chassis. In the presentlypreferred, contemplated, commercial embodiment, the weld 60 is a metalinert gas weld that extends for about 1.5 inches in length along thetubing.

The chassis 12 illustrated in the figures is a single, unitary length ofa tubular frame member (i.e., tubing). It will be appreciated that inother alternative designs (not illustrated), the chassis 12 couldcomprise two or more separate, tubular frame members. However, in thepreferred form of the present invention, the chassis 12 includes only asingle, unitary, tubular frame member, and this has the advantage ofminimizing, or at least reducing, the number of connections or jointsthat exist in the chassis 12.

The novel chassis 12 of the present invention, when made as describedabove, permits the use of stock tubing that is readily available fromtubing manufacturers. Further, the chassis 12 accommodates theconnection of one load bearing portion of the tubular frame member toanother portion of the same tubular frame member in the chassis withoutrequiring the use of unusual and expensive manufacturing techniques.

Further, the chassis 12 permits the use of a tubular frame member with areduced wall thickness that requires less material and thus reducescosts. Flexural rigidity of one part of the frame member in a particularloading direction of interest may actually be increased even though theflexural rigidity of that part of the tubular frame member with respectto certain other loading directions may be decreased (in such otherloading directions where higher flexural rigidity is not requiredbecause the loading in such other directions is not anticipated to be ashigh, or where the chassis otherwise provides increased rigidity as aresult of a connection with another portion of the tubular frame memberor with a reinforcing member of the chassis).

By appropriate orientation of the elongate transverse cross-sectionportion of the tubular frame member, that portion of the frame membercan exhibit sufficient flexural rigidity in a desired direction whereneeded to accommodate the imposed load. For descriptive purposes, thetubular frame member used in the preferred, contemplated, commercialembodiment may be characterized as having a first part that includes theend region 50 that may be regarded as a “first connection portion” 50,and the tubular frame member may be further characterized as having asecond part that includes at least some of the length of the elongatetransverse cross-section region 30 that may be regarded as a “secondconnection portion” 30. The first connection portion 50 and secondconnection portion 30 may each then be characterized as defining agenerally longitudinal central axis. The first connection portion 50 isdisposed on top of the second connection portion 30 so that thelongitudinal central axes of each connection portion 50 and 30 isaligned and generally parallel. If the frame member portion 30 isoriented so that the longer dimension of the elongate transversecross-section is generally parallel to the direction of force of gravitywhen the shopping cart is in its normal use orientation, the chassis 12can withstand the intended (i.e., “design”) loading in the verticaldirection (e.g., including the weight of the basket 16 and contents thatmay be placed therein).

The inventors have conducted strength tests of the illustrated chassis12, and have compared the test results with results from identical testsperformed on a comparison chassis having a similar configuration exceptthat the comparison chassis tubular frame member had an annularcross-section over its entire length and had no portion with anelongated transverse cross-section. Those tests showed that the chassisof the present invention, when formed from 14 gauge steel tubing, wasstronger in the vertical direction than the comparison chassis formedfrom thicker, 12 gauge steel tubing. The 12 gauge tubing wall thicknessis about 0.095 inch, whereas the 14 gauge tubing wall thickness is onlyabout 0.070 inch.

The strength of the chassis of the present invention, and the strengthof the comparison chassis were measured under static loading in thevertical direction (i.e., parallel to the direction of gravity when thechassis is in its normal use orientation), and the amount of loading orforce to cause a one quarter inch permanent deflection was measured. Forthe chassis of the present invention formed from 14 gauge steel, theloading at one quarter inch permanent deflection was 1050 pounds,whereas the comparison chassis formed from 12 gauge tubing (which wasround over its entire length) could withstand only 900 hundred poundsload before reaching one quarter inch permanent deflection.

In the presently preferred, proposed, commercial embodiment of theinvention, the outside diameter of the annular wall portions of thetubular frame member is about 1.0 inch. In each of the deformed portionsor regions 30, the total height of the elongate, transversecross-section is 1.25 inches, and the total width of the elongate,transverse cross-section is 0.675 inch. The wall thickness of eachelongate, transverse cross-section portion 30, after its deformationfrom the original annular configuration of the round stock tubing, isstill about 0.070 inch. The length of each portion 30 is about 13inches.

It will be readily apparent from the foregoing detailed description ofthe invention and from the illustrations thereof that numerousvariations and modifications may be effected without departing from thetrue spirit and scope of the novel concepts or principles of thisinvention.

1. A shopping cart chassis comprising: at least one tubular frame memberthat has a length and at least one lengthwise bend and wherein at leasta first part of the length of said frame member has a wall with a hollowcylindrical configuration defining an annular transverse cross-section;at least a second part of the length of said frame member has a wallwith a hollow configuration defining an elongate transversecross-section having a longer dimension and a shorter dimension; saidsecond part of said frame member is oriented so that said longerdimension of said elongate transverse cross-section is generallyparallel to the direction of the force of gravity when said shoppingcart is in its normal use orientation; said frame member first partincludes a first connection portion; said frame member second partincludes a second connection portion; said first and second connectionportions each define a generally longitudinal central axis; said firstconnection portion is disposed on top of said second connection portionwith said longitudinal central axes of each connection portion alignedgenerally parallel; and a weld joins said first connection portion withsaid second connection portion.
 2. The chassis in accordance with claim1 in which said frame member second part wall that defines said elongatetransverse cross section has two spaced-apart parallel straight sectionsjoining two semi-circular sections.
 3. The chassis in accordance withclaim 1 in which said first part of said frame member has a generallyuniform wall thickness; said first part wall thickness and said secondpart wall thickness are substantially equal.
 4. The chassis inaccordance with claim 1 in which said frame member is steel.
 5. Thechassis in accordance with claim 1 in which said frame member has atleast one transition portion connecting the annular transverse crosssection of said first part with the elongate transverse cross section ofsaid second part.
 6. A shopping cart chassis comprising: at least onetubular frame member wherein at least a first part of the length of saidframe member has a wall with a hollow cylindrical configuration definingan annular transverse cross-section; at least a second part of thelength of said frame member has a wall with a hollow configurationdefining an elongate transverse cross-section having a longer dimensionand a shorter dimension; and said second part of said frame member isoriented so that said longer dimension of said elongate transversecross-section is generally parallel to the direction of the force ofgravity when said shopping cart is in its normal use orientation.
 7. Thechassis in accordance with claim 6 in which said frame member secondpart wall that defines said elongate transverse cross section has twospaced-apart parallel straight sections joining two semi-circularsections.
 8. The chassis in accordance with claim 6 in which said firstpart of said frame member has a generally uniform wall thickness; saidsecond part of said frame member has a generally uniform wall thickness;and said first part wall thickness and said second part wall thicknessare substantially equal.
 9. The chassis in accordance with claim 6 inwhich said frame member has at least one lengthwise bend; said framemember first part includes a first connection portion; said frame membersecond part includes a second connection portion; said first and secondconnection portions each define a generally longitudinal central axis;said first connection portion is disposed adjacent said secondconnection portion with said longitudinal central axes of eachconnection portion aligned generally parallel; and a weld joins saidfirst connection portion with said second connection portion.
 10. Thechassis in accordance with claim 6 in which said frame member is steel.11. The chassis in accordance with claim 6 in which said frame memberhas at least one transition portion connecting the annular transversecross section of said first part with the elongate transverse crosssection of said second part.